Exposure to nicotine enhances acquisition of ethanol drinking by laboratory rats in a limited access paradigm

Observations in humans suggest that the initial use of tobacco occurs in cl ose temporal proximity to experimentation with alcohol. There have been rel atively few research reports, however, examining possible interactions betw een these two agents. The present experiments examined the effect of nicoti ne exposure on the acquisition of ethanol drinking behavior in a limited ac cess procedure. In experiment 1, rats were presented with 1-h access to eth anol solutions of increasing concentration for a period of 20 days. Subcuta neous injections of nicotine (0.6 or 1.2 mg/kg salt) or vehicle were admini stered 30 min prior to each ethanol presentation. Experiment 2 used a simil ar method, but rats were presented with water along with ethanol during the 1-h test session. Mecamylamine, a nicotinic receptor antagonist, was admin istered 30 min prior to the nicotine treatment. Nicotine was seen to produc e a dose-dependent increase in ethanol drinking behavior which commenced at the 5% ethanol concentration and continued at 8% and again at 10%. In the second experiment, mecamylamine was observed to block completely the nicoti ne-induced increase in ethanol drinking behavior. The findings suggest that exposure to nicotine can facilitate the acquisition of ethanol drinking be havior in naive rats and that this effect is mediated by nicotine's interac tion at the nicotinic-cholinergic receptor.